Ricoh B079, Service Manual

Page: 892 / 948

Detailed
De
sc
ri
ptions
DEVELOPMENT
SM 6-61 B079/B082
6.9.4 DEVELOPMENT BIAS
Mechanism
In a negative-positive development
system, black areas of the latent image
are at a low negative charge (about –
150 V) and white areas are at a high
negative charge (about –950 V).
To attract negatively charged toner to
the black areas of the latent image on
the drum, the high voltage supply board
[A] applies a bias of –600 volts to the
development roller throughout the image
development process. The bias is
applied to the development roller shaft
[B] through the bias terminal spring [C]
and bias terminal [D].
The development bias voltage (-600 V) can be adjusted with SP2-201
(Development Bias).
Correction for paper width and thickness (by-pass tray only)
The by-pass tray can be used for non-standard paper narrow than sizes accepted
by the paper trays. Thicker paper, OHP sheets, etc. can also be loaded in the by-
pass tray but adjustments must be performed with the SP modes listed below in
order to avoid jams and misfeeds.
SP Mode SP Name
SP2-201-1 Development Bias Width 216 -297 mm (Default: -510 V)
SP2-309-1 Paper Lower Width [a] Width limit: (Default: 150 mm)
SP2-309-2 Paper Upper Width [b] Width limit: (Default: 216 mm)
SP2-914-3
Process Control Setting (B γ )
Adjust 10V/step (Default: 200 V)
SP2-914-4
Process Control Setting (B
δ
)
Adjust 10V/step (Default: 50V)
The way that these SP modes are used is shown below.
S SP29143
Default: -510 + 200 V
For example, with the default settings, if the paper width fed from the by-pass tray
is 200 mm, the development bias voltage will be –600 + 50 V.
B004D404.WMF
0 mm
SP 2-309-1
Default: 150 mm
SP 2-309-2
Default: 216 mm
297 mm
Voltage:
SP2-201-1 + SP2-914-3
Default: -600+250 V
Voltage:
SP2-201-1 + SP2-914-4
Default: -600+50 V
Voltage:
SP2-201-1
Default: -600 V
B004D508.WMF
[A]
[B]
[C]
[D]
Rev. 09/2003
⇒
⇒
S SP29143
Default: -510 + 200 V
S SP29144
Default: -510 + 50 V
SP22011
Default: -510 V
⇒